Electric valve system



7 2, 1942- G. a. SOMERVILLE 2,306,229

ELECTRIC VALVE SYSTEM Original Filed March 30, 1942 fi i I I l \l s RECTIFIER *4 CON TROL CIRCUIT Fig.3. V

PHASE SH/FTER PEA/(ER D Fig.4. D, F\/\ /Y VA Inventor: GTQt-h G. Somervil Is,

is Att orney Patented Dec. 22, 1942 ELEUIRIC VALVE SYSTEM Gareth G. Somerville, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Original application March 30, 1942, Serial No. 436,813. Divided and this application July 10, 1942, Serial No. 450,439

9 Claims.

My invention relates to electric valve systems and more particularly to electric valve apparatus for energizing load circuits, such as welding circuits, from alternating current supply circuits.

This application is a division of my copending ment of my invention as: applied to a welding system and in which a capacitance is charged patent application Serial No. 436,813, filed March 30, 1942, and which is assigned to the assignee of the present application In some industrial applications, such as electric resistance welding equipments, it is frequently desirable to transmit to a load circuit, or Welding circuit, a predetermined amount of current of relatively short duration. In accordance with the teachings of my invention described hereinafter, I provide new and improved electric valve equipment wherein this object may be accomplished by employing apparatus to greater advantage, thereby decreasing the size of the equipment to supply a given amount of to the load or welding circuit.

It is an object of my invention to provide new and improved electric valve translating apparatus.

It is another object of my invention to provide new and improved electric valve welding apparatus.

It is a further object of my'invention to provide new and improved electric valve welding ap- 'paratus wherein predetermined pre-heating or post-heating current may be transmitted to the welding circuit and wherein the welding current is applied to the work at predetermined times.

It is a still further object of my invention to provide new andimproved electric valve welding apparatus wherein alternating current is continuously supplied to the welding circuit during a predetermined interval of time, and in which impulses of welding current are superimposed on the alternating current at predetermined recurring times.

Briefly stated, in one of the illustrated embodiments of my invention, I provide new and in proved electric resistance welding equipment of the energy storage type wherein alternating current is continuously supplied to the welding circuit to pre-heat or post-heat the work, and wherein the welding operation is accomplished by the periodic change in the state of energization of the energy storage means, such as a capacitance.

For a better understanding of my invention,

- reference may be had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the power energy from a supply circuit and discharged through the welding transformer in order to produce the Weld, and in which the power transformer is premagnetized or presaturated to prevent cumulative unidirectional magnetization of the transformer by the discharge of the capacitance; Fig. 2 represents certain operating characteristics of the arrangement shown in Fig. 1. Fig. 3 diagrammatically illustrates another embodiment of my invention in which alternating current is supplied to thewelding circuit, and in which the current which produces the weld is superimposed on the alternating current by means of the discharge of a capacitance; Fig. 4 represents an appended claims. Fig. 1 of the accompanying drawing diagrammatically illustrates an embodioperating characteristic of the circuit shown in Fig. 3. a

Referring now to Fig. 1 of the drawing, I have there illustrated my invention as applied to a system for energizing a welding circuit l. A capacitance 2 is charged from a suitable supply circuit, such as an alternating current supply circuit 3, through a rectifier 4, to charge the capacitance to the polarity indicated. The capacitance 2 is discharged to energize the welding circuit through a circuit including electric valve means 5 and transforming means 6. The transforming means 6 is provided with primary winding means 1 and secondary winding means 8 which is connected to the welding circuit l. The transforming means 6 is also, of course, provided with a magnetic core structure. In order to prevent cumulative unidirectional magnetization of the transforming means 6, occasioned by successive discharges'o'f the capacitance 2, I provide means for impressing on the core structure of the transforming means 6 a magnetomotive force,

preferably unidirectional, and which is in opposition to the magnetomotive force which is caused by the discharge of a capacitance 2 through the transforming means 6. This unidirectional magnetization of the transforming means 6, whiciN' is in opposition to that produced by the discharge of capacitance 2, also aflords greater utilization? of the core structure of the transforming means 6, thereby making it possible to deliver a greater amount of energy or power to the Welding circuit I, or permitting the use of a small transforming means to deliver a given amount of power. The premagnetizing or presaturating means may comwelding circuit l.

rent is transmitted to a portion of the primary winding means I from circuit 8 which may be energized from a direct current supply circuit ll, of the polarity indicated, through a switch [2. The magnitude of the unidirectional magnetomotive force impressed on the core structure of the transforming means 6 may be controlled or determined by any suitable means, and for the purpose of illustrating a means for accomplishing this result I have represented a variable impedance means, such as a variable resistance 13, connected in series relation with the upper portion of the primary winding means 1 and circuit II.

The electric valve means is preferably of the type employing an ionizable medium, such as a gas or a vapor, and in which the conduction of current is controlled by the potential impressed on a control means such as an immersionigniter control member I. The electric valve means 5 conducts current when a suitable current is transmitted to the control member It. A unidirectional conducting device l5 may be connected in series relation with control member 14, and the time of discharge of the capacitance 2 through the operation of electric valve means 5 may be controlled by means of a switch H; which is connected in circuit with the control member I. Switch l6 may be a switch of the type which, upon actuation, closes its contacts for a relatively short interval of time, so that the energizing voltage or current is supplied to the control member it during a correspondingly short interval of time.

A control circuit l1 may be employed to supply current to the control member l4, and this circuit may comprise a timing device such as that explained hereinafter in connection with the arrangement of Fig. 3, or may merely include a peaking transformer and phase shifting means for supplying current to the control member ll through the unidirectional conducting device I8 and switch l8.

The operation of the embodiment of my invention shown in Fig. 1 willbe explained by considering the system when it is desired to effect the transmission of an impulse of current to the The premagnetizing or presaturating circuit of the transforming means 6 establishes therein a unidirectional magnetization of predetermined magnitude which is in a direction opposite to that which is effected by the discharge of capacitance 2. In order to obtain the greatest utilization of the iron of the transforming means, the core structure should be magnetized to a point of substantial saturation.

Upon operation of switch [6, at a definite point in the cycle of the voltage of supply circuit 3, an impulse of current is transmitted to control member I of electric valve means 5, rendering the electric valve means 5 conducting and effecting discharge of capacitance 2 through a circuit including the anode-cathode circuit of electric valve means 5 and the lower portion of the primary winding means 1. It will be noted, of course, that this current traverses the primary winding means 1 in a direction opposite to the direct current supplied to this winding by means of circuit 9. The incident rate of change of flux occasioned by the capacitance discharge current through the primary winding means 1 induces a. voltage in the secondary winding means 8, and consequently causes the transmission of an im pulse of welding current to the welding circuit l.

As soon as the welding operation is eflected,

the residual magnetization effect, which would be present in the absence of the unidirectional magnetization caused by circuit 9, is neutralized thereby maintaining an initial predetermined magnetization of the core structure of the transforming means 6 of the desired polarity, and thereby preventing the cumulative unidirectional magnetization of the core structure which would be caused by successive discharges of capacitance 2 through primary winding means i. In this manner, the discharge of capacitance 2 is always initiated at the same predetermined magnetization of the core structure, thereby obtaining uniformity in the magnitude of the welding current and uniformity in the welds produced.

It is to be understood that the control circuit and switch l6 shown in Fig. 1 are diagrammatic representations of the control circuit which may be employed. For example, the switch l6 may be of the type which maintains its contacts closed for only a short interval of time in response to a single circuit controlling operation, so that the electric valve means 5 is not maintained in a conducting condition for an appreciable period. This requirement is apparent in view of the fact that it would be undesirable to maintain the electric valve means 5 conducting immediately after each discharge of the capacitance 2.

Curve A of Fig. 2 represents the welding current supplied to circuit I occasioned by discharge of capacitance 2, and curve B represents the voltage of the alternating current circuit 3. The control circuit I! may be arranged to obtain synchronization of the impulses of discharge or welding current with respect to the voltage of the alternating current circuit 3.

Fig. 3 diagrammatically illustrates another embodiment of my invention wherein the welding circuit i is energized from an alternating current supply circuit 3 through a transforming means is. The welding current in this arrangement may be applied to work l9 through a pair of wheels 20 which act as electrodes for those applications in which it is desirable to effect line welding operations. The transforming means I3 is provided with primary winding means 20 which may include a plurality of taps 2| and 22.

Alternating current of predetermined magnitude is continuously supplied to the work I9 from the supply circiut 3, in order to produce the desired pre-heating or post-heating of the work. The magnitude of the alternating current transmitted to the work I!) may be determined by control of the voltage of the supply circuit 3, or by the interposition between supply circuit 3 and transforming means I8 of suitable voltage controlling means such as an adjustable trans former or autotransformer (not shown).

The Welding operations or the welds produced on the work I9 are effected by means of energy storage apparatus which may comprise a capacitance 23. More specifically, the welds are produced by a change in the state of the energization of capacitance 23 which is connected to the transforming means, such as primary winding means 20, through switches 24 and 25. Switches 24 and 25 may be arranged to engage selectively various taps of the group of taps 2| and 22, thereby controlling the magnitude of the welding current transmitted to the work l9 upon the change in energization of the capacitance 23.

In the embodiment of my invention illustrated in Fig. 3 the capacitance 23 is charged from a suitable source of direct current 26 through a circuit which may include inductances 21 and 23 and adjustable resistances 2B and 30. These elements prevent the feed-back oi appreciable current or energy to circuit 28 upon discharge of capacitance 23.

As a means for discharging the capacitance 23 to produce the welds, I employ suitable circuit controlling'means, such as electric valve means 3|, which may be connected between one of the switches, such as switch 24. The electric valve means 3| is also preferably of the type employing an ionizable medium, such as a gas or a vapor, and may include control means which normally maintains the electric valve means nonconducting and which renders the valve means conducting at desired times. The control means may comprise an immersion-igniter control member 32 which initiates an arc discharge within the electric valve means upon the transmission of a predetermined minimum value of current to the control member.

I provide a control circuit 33 for transmitting an impulse of control current to control member 32, or for transmitting recurring or periodic impulses of current to the control member 32. Control circuit 33 may comprise a rectifier 34 which charges a capacitance 35 through a transformer 36 and a unidirectional conducting device or electric valve 31. The rectifier 34 may be energized from the supply circuit 3. Capacitance 35 is discharged through a circuit including inductance 38 and an electric valve 39 to supply an impulse of current to control member 32. It will be noted that the control member 32 is connected in the discharge circuit for the capacitance 35. The electric valve 39 may be of the type employing an ionizable medium, such as a gas or a vapor, and may include a grid 40 which determines the time at which the discharge of the capacitance 35 is initiated.

I provide timing means 4| which determines the time at which the electric valve means 3| is rendered conducting, and also may determine the periodicity of the welding impulses transmitted to the welding circuit I. This timing means 4| may be of the single valve inverter type in which a capacitance 42 is charged and periodically discharged to produce a timing voltage which determines the, times of conduction of electric valve 39.

Referring more particularly to the timing means 4|, the capacitance 42 is charged from a source of direct current 43 and is discharged through a circuit including an inductance 44 and an electric discharge device 45 having a.

/ grid 46. A voltage divider including a resistance 41 is connected across the direct current circuit 43, and is provided with an adjustable connection 48 which is connected to the cathode of electric valve 40. An adjustable resistance 49 is connected in the manner indicated and is provided with an adjustable tap 50 which is connected to the grid 40 of electric valve 39 through a voltage biasing means, such as a battery The negative potential of battery 5| tends to maintain the electric valve 39 nonconducting except during those intervals when the periodic voltage produced by timing means 4| attains a value sufilciently positive to render the electric valve means 39 conducting. The periodicity of the periodic impulses produced by timing means 4| may be controlled by determining the position of contact 52 of resistance 41.

In order to synchronize the time of occurrence of the impulses of welding current caused by discharge of capacitance 23, I employ a peaking transformer 53 which is connected between contact 52 and grid 48 of electric discharge device 45. The peaking transformer 53 may be energized from alternating current supply circuit 3 through a suitable phase shifting device 54. Adjustment of the phase shifter 54 determines the time during the cycle of voltage of supply circuit 3 at which the periodic impulse produced by timing means 4| occurs and consequently determines the time at which the capacitance 23 is discharged to supply the welding current.

The operation of the embodiment of my invention shown in Fig. 3 will be explained by considering the system when it is performing a line welding operation; that is, when it is operating to transmit impulses of welding current to the work I9 at predetermined recurring times. Alternating current is continuously transmitted to the work l9, thereby producing the desired either pre-heating or post-heating of the work IS. The capacitance 23 which is charged from the direct current source 26 is periodically discharged to produce the impulses of welding current at regular recurring times.

'Reierring particularly to the discharging operation of the capacitance 23, the capacitance is discharged through a circuit including switch 25, primary Winding means 20, .switch 24 and the anode-cathode circuit of electric valve means 3|. Consequently, the impulse of current produced by the discharge of the capacitance 23 is superimposed on the alternating component of current. This feature of operation is illustrated in Fig. 4 where the alternating component of current is represented by the curve C and where the welding current produced by discharge of capacitance 23 is represented by the peaks D and D which are superimposed on the alternating sinusoidal current.

Electric valve 3| is rendered conducting by control circuit 33 which periodically discharges the capacitance 35 to energize the control member 32. The timing means or circuit 4| produces a periodic timing voltage synchronized with respect to the voltage of supply circuit 3 and renders the valve 39 in control circuit 33 conducting periodically. Due to the negative biasing potential impressed on grid 40 of electric valve 39 by battery 5|, electric valve 39 is normally maintained nonconducting except at those times when the periodic voltage produced by timing means 4| attains a value sufficient to overcome the effect of the battery voltage. By adjustment of timing circuit 4|, the periodicity of the welding current impulses may be controlled or adjusted.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devicesdiagrammatically shown, it will be obvious to those skilled in th art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an alternating current supply circuit, a load circuit, transforming means connected between said supply circuit and said load circuit and including. primary winding means, a capacitance, mean for charging said capacitance, and means for discharging said capacitance so that the current transmitted to said load circuit comprises a substantially continuous alternating current wave and a superimposed impulse of current caused by the discharge or said capacitance.

3. In combination, an alternating current supply circuit, a welding circuit, transforming means connected between said circuits and comprising primary winding means, said transforming means bein continuously connected to said supply circuit so that alternating current is transmitted to said welding circuit, a capacitance, means for charging said capacitance, and means connected between said capacitance and said transforming means, said transforming means being connected permanently to said supply circuit so that alternating current is continuously supplied to said welding circuit, a capacitance, a charging circuit for said capacitance, and means connected between said capacitance and said primary winding means for periodically changing the state of energization of said'capacitance and for superimposing on the alternating component of current transmitted to said welding circuit an impulse of current incident to the change in the state of energization of said capacitance.

4. In combination, an alternating current supply circuit, a welding circuit, transforming means comprising primary winding means connected to said alternating current supply circuit and having secondary winding means connected to said welding circuit, said transforming means being excited from said supply circuit for supplying alternating current continuously to said welding circuit, a capacitance, a direct current circuit connected to said capacitance, inductive means connected between said direct current circuit and said capacitance, and means for controlling the energization of said capacitance through at least a portion of said primary winding means and for superimposing on the alternating component of current transmitted to said welding circuit an impulse of current incident to the change in the state of energization of said capacitance,

5. In combination, an alternating current supply circuit, welding circuit, transforming means {or periodically rendering conducting said electric valve means and for discharains said capacitance and for superimposing on the alternating component of current transmitted to said welding circuit an impulse of current incident to the discharge of said capacitance.

6. In combination, an alternating current supply circuit, a welding circuit, transforming means connected between said supply circuit and said welding circuit and including primary winding means, saidtransforming means being connected to said supply circuit so that alternating current is continuously supplied to said welding circuit, a capacitance, a direct current circuit connected to said capacitance, normally nonconducting electric valve means connected between said capacitance and said transforming means, and means supply circuit so that alternating current is transmitted to said welding circuit to preheat the work, a capacitance, means for charging said capacitance, and means for discharging said capacitance through said transforming means and for superimposing on the alternating current transmitted to said welding circuit an impulse of current to effect the welding operation.

8. In combination, an alternating current supply circuit, a welding circuit, transforming means connected between said circuits and comprising primary winding means, a capacitance, means for charging said capacitance, means connected between said capacitanc and said transforming means for discharging said capacitance to eilect the welding operation, and means for continuously energizing said transforming means from said supply circuit so that alternating current is transmitted to said welding circuit. 4

9. In combination, an alternating current supply circuit, a welding circuit, transforming means connected between said circuit and comprising primary windin means, a capacitance, means for charging said capacitance, means connected beconnected between said supply circuit and said welding circuit and including primary winding means, said transforming means being connected to said supply circuit so that alternating current tween said capacitance and said transforming means for discharging said capacitance and for transmitting an impulse of welding current to the circuit,-and means for continuously energizing the primary winding means from said supply circuit and for supplying alternating current to said work prior and subsequent to the welding operation.

GARETH G. SOMER VILLE. 

